Missing documentation for Twitter streamer

[Denis Magda]

Igniters,

Seems that we don't a documentation for the recently added Twitter
streamer as well (as we don't have for MQTT one). [1]

Is anyone interested in adding it on readme.io?

Lalit Kumar Jha, probably you will be able to do this cause the
functionality was contributed by you. Let us know if you have time for that.

[1] https://issues.apache.org/jira/browse/IGNITE-2413

--
Denis